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Discussion Starter #1
Silicone??

That's what my instructions are saying, to use clear silicone! I had always heard they were epoxied in place, but the instructions say something about this way being better because it's removable. (The PO was very much in love with clear silicone, and used it ALL OVER my boat, and every time I find myself sanding it off I want to go find him and wring his bloody neck).

BTW, the instructions also go on to recommend glycol to fill the unit, which is something else I wouldn't have expected. Are they talking ordinary antifreeze?

As I am a sailboat neophyte, I appreciate any words of wisdom, thanks!
 

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Living the dream
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Is this to shoot through a solid f/g hull? In that case silicon will work perfectly with the following caveats; 1) make sure the transducer gets a clear reading through the hull at the desired mount location BEFORE mounting it permanently in place. KY jelly or vaseline makes a great temporary medium for this and 2) don't allow any air bubbles to form in the silicon during the installation process.
 

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Courtney the Dancer
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I've mounted several in hull transducers using silicone and it works great. I used a zip lock bag with mineral oil in it to locate a good location on the hull, then apply a large blob (technical term) of clear silicone. Hold the tip of the tube in the center of the location you've chosen and just squeeze it out around the tip, that results in the fewest bubbles forming. Just let the ducer settle down into it (angle it a bit at first to let air escape) and secure it with duct tape or something if it tends to move downhill on you.
 

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I have installed one with silicone and many using epoxy which is recommended by most depth sounder manufacturers. Epoxy is the best in my opinion, bubbles aren't an issue. There is no real need to make it removable.

To find a good location I just place the transducer in a baggie of water and move it around until it works.

Here is a link to West Epoxy's instructions to install a transducer.

WEST SYSTEM | Modifying and Customizing Boats - Depth sounder installation
 

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I have installed one with silicone and many using epoxy which is recommended by most depth sounder manufacturers. Epoxy is the best in my opinion, bubbles aren't an issue. There is no real need to make it removable.

To find a good location I just place the transducer in a baggie of water and move it around until it works.

Here is a link to West Epoxy's instructions to install a transducer.

WEST SYSTEM | Modifying and Customizing Boats - Depth sounder installation
mitiempo,

I don't mean to be contrary, but the statement, "There is no real need to make it removable." sounds like some one who has never purchased a used boat, or owned a boat for more than a few years. EVERYTHING always needs to be replaced at some time or another!

I guess I am just a geezer. ;)

Greg
 

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It is removable, but not to re-use. A good whack with a hammer sideways will remove it. No reason to if it is working though.
 

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There are few things on a boat that a good whack with a hammer won't set right.
..................

..........
Or the proper application of the correct amount of explosive! :D

Greg
 

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Discussion Starter #10
Dixie,

You might want to take a look at one of the projects web pages. It's at;
Guenevere's Projects, Depth sounder
and shows how we did a no hole depth gauge on our boat.

Greg
Greg, that's essentially how my transducer (Airmar P79) mounts. It comes with a plastic cylinder "base", which is cut at an angle and flanged on one end. This end is placed on the hull, rotated until the top end is perfectly level, and siliconed down. After curing, it gets filled with propylene glycol and the 'ducer gets sealed inside.

I'm still surprised at the use of clear silicone, but if it worked for you, I'm sure it'll work for me! And I might very well have to move the 'ducer, since I was unable to test it with the boat in the water prior to mounting. I have it placed in the area recommended by Airmar, and where other owners of Catalina 22's have mounted theirs, so I hope my odds of success are at least pretty fair.

I'm not sure why Airmar recommends the propylene glycol, either, but I'll just roll with it. After some research, I've found Prestone "Lo-Tox" antifreeze uses propylene glycol in a concentration of 90-100%, according to their MSDS's. So, it's off to the auto parts store in the AM. :)
 

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I'm not sure why Airmar recommends the propylene glycol.....
So it doesn't freeze and crack the tube or damage the transducer.

This was more common in the past than now. I have had several boats with the transducer in fluid filled tubes. On my current boat it was done this way and the fluid had all leaked out. It was aft, wrong place anyway.

Most depth sounder manufacturers recommend epoxy now as I posted, a few silicone, but rarely do they recommend the fluid filled tube - just attaching the transducer directly to the inside of the hull is the easiest and most maintenance free way.
 

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I'm not sure why Airmar recommends the propylene glycol, either, but I'll just roll with it. After some research, I've found Prestone "Lo-Tox" antifreeze uses propylene glycol in a concentration of 90-100%, according to their MSDS's. So, it's off to the auto parts store in the AM. :)
Good luck and hope it works first time for you!

I used mineral oil and it's been working for many years. BUT, we are in warm to tropical waters ALL of the time.... :D

Most likely they recommend the poly-gly in case the craft is in a cold climate. If I was in an area where it drops below freezing, I would most likely go that way.

POST PHOTOS!

Greg
 

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If I remember the recommendations for my P79
indicated that epoxy will become brittle over time, which would lead to leaking. I used 3M 4200 as it was what I had handy. I've since heard that some adhesives may attack the plastic, not sure if 4200 will. Silicone is probably a safer bet.

The Propylene Glycol of course makes sense for reasons of freezing. I took a chance and mounted it permanently without testing function and it works great. I do know that it will not work without being filled with liquid. I also applied a food grade lubricant to the threads as I do with my strainer basket lids.
 

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If I remember the recommendations for my P79
indicated that epoxy will become brittle over time, which would lead to leaking.
Polyester gets brittle - epoxy shouldn't.

The transducers are potted in epoxy - nothing will have an effect on it.

That is the beauty of attaching the transducer to the hull with whatever you choose instead of a liquid filled tube - nothing to leak.
 

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Polyester gets brittle - epoxy shouldn't.

The transducers are potted in epoxy - nothing will have an effect on it.

That is the beauty of attaching the transducer to the hull with whatever you choose instead of a liquid filled tube - nothing to leak.
The instructions state that epoxy is too brittle. Here are the Warnings within the Installation Instructions.

WARNING
: Always wear safety goggles and a dust
mask to avoid personal injury.
CAUTION
: The fiberglass hull below the transducer
must be solid. The transducer
will not transmit through
coring material such as foam or balsa wood.
CAUTION
: Do not use an epoxy adhesive because it
is too brittle.
CAUTION
: Never pull, carry, or hold the transducer by
the cable. This may sever internal connections.
CAUTION
: Never use solvents. Cleaners, fuel,
sealants, paint, and other
products may contain strong
solvents, such as acetone, which attack many
plastics, greatly reducing their strength.
IMPORTANT
: Please read the inst
ructions completely
before proceeding with the installation. These
instructions supersede any ot
her instructions in your
instrument manual if they differ
 

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The instructions state that epoxy is too brittle. Here are the Warnings within the Installation Instructions.
Epoxy is no more brittle than the polyester you are attaching it to. Having used epoxy for over 25 years (West System as well as other brands) I have never found it brittle. As I posted the transducer face can be epoxied to the hull without the tube and fluid. It has worked fine for my customers as well as on my own boats in every instance - for Airmar as well as other brands of transducers.
 

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Discussion Starter #19
Brian, I was intrigued by the West System method in the link you posted, is that the way you get the unit perfectly level, without the use of an angled base of some kind?

 
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